When a fleet of electrically driven vehicles such as golf carts is to be kept in operation, the vehicles must either be taken out of service for recharging, thereby enlarging the total number of vehicles required in the fleet for a given level of service, or the vehicles must be provided with readily changeable battery packs so that only the batteries, and not the vehicles, need to be taken out of service for recharging.
Since the provision of readily replaceable battery packs thereby considerably reduces fleet requirements for a given level of service, there has long been a need for a practical system for providing replaceable battery packs. Generally the removal and replacement of batteries on a one-by-one basis is too slow and therefore impractical. On the other hand, battery packs consisting of a series of batteries have generally been too heavy and awkward to handle to accomplish ready replacement without the provision of heavy hoisting or lifting means such as power hoists or fork lift trucks which require provision of related service space and facilities and tend to create an "industrialized" ambiance which is unacceptable in a country club operation.
The present invention provides for the ready replacement of battery packs by a light dolly or handtruck so that battery packs can be quickly and easily replaced in a fleet of vehicles and a high level of service can be maintained for a given number of vehicles.
The replaceable battery packs that have been provided in the prior art have generally been mountable and demountable on the vehicle chassis or frame. Since in an electric vehicle, the weight of the batteries is a significant proportion of the total vehicle weight, the requirement for battery support significantly contributes to frame strength requirements.
In the present invention, battery packs are supported on the rear axle of the vehicle largely independently of bending forces on the frame. The resultant lighter frame requirement saves weight and reduces the battery requirement, also saving weight. The two savings have a synergistic weightsaving effect and together contribute to the practicality of the use of manually operated dollies or handtrucks for the quick change of the battery packs.
One of the important considerations in fleet operation is the amount of space required for vehicle and battery storage. It is desirable to avoid providing large areas of garage or shed space. Unless the batteries can be readily removed, it is impractical to save space by storing a fleet of vehicles in an upright position, and even when this is done the additional requirement of storing the batteries contributes greatly to space requirements.
The present invention makes it possible to quickly and easily store vehicles in an upright position, since the batteries can be readily removed. Furthermore, after the vehicles have been put in upright position, the batteries can be readily replaced and supported off the ground by the vehicles. Off-the-ground support is good practice for battery storage.
This procedure effects further space-saving by reducing the total space requirement to that required for upright storage of the vehicles alone, with the only excess requirement being that represented by additional battery packs beyond the number of vehicles in the fleet.